Stricter state sentencing laws in Washington have swelled the ranks of inmates serving life sentences to nearly one in five.

And some lifers who opted to go to trial are serving much longer sentences than others who committed the same crimes and plea-bargained — raising questions about equitable treatment of prisoners.

Those are among the findings in a new analysis by undergraduate honors students in the University of Washington’s Law, Societies & Justice program, who sought to determine the number of lifers in Washington prisons, the legal processes that lead to life sentences and the cost of housing those inmates, many of whom will die behind bars.